This invention relates to a timing controller for controlling the timing for operating a mechanically controllable machine part according to the motion of an object or a batch of articles which may be freely falling in space. The invention relates also to an improved form-fill-seal type packaging machine which incorporates such a timing controller.
Among the devices requiring such a timing controller is not only a vertical pillow type form-fill-seal packaging machine but also a sorter of the type using an air jet to selectably remove or not remove objects which are being transported at a high speed or falling freely in air. A vertical pillow type form-fill-seal packaging machine is generally controlled such that a tubularly formed elongated bag-making material (herein referred to as xe2x80x9cthe filmxe2x80x9d) is transversely sealed thermally between a pair of seal jaws, while the film is being transported vertically downward and articles to be packaged are intermittently dropped from above, so as to thereby simultaneously close the bag into which articles have already been dropped and to form the bottom of the next bag into which a new article batch is to be dropped. Thus, if the timing of closing the seal jaws to seal the tubularly formed film is incorrectly set, some of the articles being dropped from above may be caught in between, thereby producing imperfectly sealed products. In order to prevent the occurrence of such events, it is. customary to adjust the timing of moving the seal jaws by using a transparent film in a test run. It now goes without saying that the sorter of the kind described above also requires a test run for adjusting the timing for releasing air jets.
Adjustments by such test runs are not a simple process. In the case of packaging relatively light articles without a definite shape such as potato chips, for example, it is extremely difficult to determine whether they are being caught near the front end or near the rear end. As a result, it take an extra effort to adjust the timing of the operation.
It is therefore an object of this invention to provide an improved timing controller adapted to display the timing of encounter between a moving object and a mechanically controllable mobile machine part in a static manner on a time axis or parallel axes such that the adjustment of the timing for operating the machine part can be carried out easily and dependably on the basis of such a visual representation even if the actual encounter between the object and the machine part takes place instantaneously.
It is another object of this invention to provide a form-fill-seal packaging machine incorporating such a timing controller.
A timing controller embodying this invention, with which the above and other objects can be accomplished, may be characterized not only as serving to control the motion of a mobile machine part according to the motion of a specified moving object but also as comprising a display device for displaying markers on a time axis or axes and control means for moving a marker on the display device and to thereby control the motion of the mobile machine part. Both a marker indicative of the time at which the moving object of interest will arrive at a specified position and another marker indicative of the time at which the mobile machine part will arrive at the same specified position will be displayed. With such a timing controller, the user can visualize the times of arrival at the specified position by the mobile machine part and the moving object of interest, and a change in the timing of arrival of the mobile machine part to the specified position can be easily effected merely by operating this control means to move a marker on the corresponding time axis.
A packaging machine, embodying this invention, of the type having transverse sealers for sealing to close a bag-forming film after articles to be packaged are dropped in may be broadly characterized as having a similar display device, as well as means for controlling the motion of these transverse sealers. The display device displays the times of arrival of the transverse sealers and the articles dropping into the bag at the clamping position where the film is clamped by the transverse sealers.
For adjusting the motion of the transverse sealers, the user specifies what is herein referred to as the xe2x80x9cdelay timexe2x80x9d which is defined as the time period between a pre-defined starting time and the time when the transverse sealers clamp the film therebetween. If a sensor is provided at a suitable position for detecting the articles being dropped, this xe2x80x9cstarting timexe2x80x9d may be taken as the time when the articles being dropped are detected by this sensor. Alternatively, the xe2x80x9cstarting timexe2x80x9d may be defined as the time when these articles are dropped, say, from a weigher disposed above the packaging machine. The time (referred to as the xe2x80x9cfalling timexe2x80x9d), taken by the dropping articles to reach the clamping position from the xe2x80x9cstarting timexe2x80x9d, no matter how defined as above, is determinable experimentally for each of different kinds of articles and is stored in a memory. When making packages of a particular kind of articles, the user may specify the kind of articles through a retrieving means which serves to retrieve from the memory the xe2x80x9cfalling timexe2x80x9d of the specified kind of articles and this retrieved information is caused to be displayed on the display device for the user to see. The user sets the delay time according to the displayed falling time.